Brighter Planet

WASHINGTON — Climate scientist Michael Oppenheimer stood along the Hudson River and watched his research come to life as Hurricane Sandy blew through New York.

Just eight months earlier, the Princeton University professor reported that what used to be once-in-a-century devastating floods in New York City would soon happen every three to 20 years. He blamed global warming for pushing up sea levels and changing hurricane patterns.

New York “is now highly vulnerable to extreme hurricane-surge flooding,” he wrote.

For more than a dozen years, Oppenheimer and other climate scientists have been warning about the risk for big storms and serious flooding in New York.

Still, they say it’s unfair to blame climate change for Sandy and the destruction it left behind. They cautioned that they cannot yet conclusively link a single storm to global warming, and any connection is not as clear and simple as environmental activists might contend.

When it comes to climate change and the increasing likelihood of catastrophic storms like Hurricane Sandy, we need a new way of discussing causation. It is absurd to say that global warming “caused” Sandy — but it’s also absurd to say that a particular cigarette “caused” a case of lung cancer. There are direct causes (the baseball that caused your broken window), and there are “systemic” causes, which are no less real for being harder to isolate. The relationship between smoking and lung cancer is one example of systemic causation, as is that between drunk driving and auto accidents, and that between increased atmospheric CO2 and the likelihood of extreme weather.